awk to count lines in column of file -

i have large file want use awk count lines in specific column $5, before the: , count -uniq entries, seem having trouble getting syntax correct. thank :).

sample input

chr1    955542  955763  +   agrn:exon.1 1   0 chr1    955542  955763  +   agrn:exon.1 2   0 chr1    955542  955763  +   agrn:exon.1 3   0 chr1    955542  955763  +   agrn:exon.1 4   1 chr1    955542  955763  +   agrn:exon.1 5   1  awk -f: ' nr > 1 { count += $5 } -uniq' input 

desired output

1 

$ awk -f'[ \t:]+' '{a[$5]=1;} end{for (k in a)n++; print n;}' input 1 

• -f'[ \t:]+'

  this tells awk use spaces, tabs, or colons field separator.

• a[$5]=1

  as loop through each line, adds entry associative array a each value of $5 encountered.

• end{for (k in a)n++; print n;}

  after have finished reading file, counts number of keys in associative array a , prints total.